This one's is a pre-production prototype, and hence the only Enigma ever to be made in the far east.. Apparently they decided that their welding and quality was better, so 3rd hand down the line I got a Columbus frame for peanuts.

This one had "Melbourne specific geometry" whatever that is…

There's no problem with OEM forks sold cheap… FYI the Roxkshox warranty is worldwide. A mate bought a pair of argyles from the states on ebay and they popped an o-ring straight away. Fishers fixed them for him for free.

I've got some 09 Reba teams and some 07 Durins. The Rebas win hands down for damping, and were cheaper (from on-one) than the Durins were at trade. The Durins do seem a tinsy bit stiffer steering though.

Are you a qualified cable weaver?

That front hose is going to cut like a saw through all those others.

You should get all the dead growth out of that jasmine too…

Bomb proof, easy to use, stable, surly angry staff…

£400 is cheap for the most used tool in your workshop.
Think about it.. You'll buy it, and never have to speak to her again, unless you find they're so good you need a second one!

same pads as SLX/XTR etc

Another thing for TJs theory.. Smaller rotors will dry off quicker in rain as there's less water to wipe/evaporate off.
Plus they will hold less grit (if you're riding in sandy conditions) and kill your pads slower.

Also.. Agree with the hope pad compound thing.. You've got to work damn hard to wear a sintered pair out… Shimano's though: nom nom nom…

I have up-niched my handlebars since SSEC.. Does that mean that I don't need to bring the handlebar moustache this time?

The thing that helps that the most is un-bending the spokes at the nuckle-head when you build them. ie. Press the bends with your thumb when you build them, or hit them with a soft hammer. Getting a straight line on the outside spokes means that they will not flex on each wheel turn, and therefore won't fatigue.

TJ I hate to bring this to you but in a wire spoked wheel or a wooden spoked wheel the forces are the same. In a wooden spoked wheel the rim is heated to red hot before being applied to the wheel. This allows it's tension to hold the wheel together after it's cooled and bound itself to the wheel. There is negative pre-tension involved, or in this case pre-compression.
Oh whoops.. there's an equivalence.
In the case of the spoked wagon wheel any increase in pressure below increases the pressure on the lower spokes and supports the hub. This is in spite of the fact that there is a force acting upon the hub from each of its spokes, restoring it to it's central position. The pre-compressive force cancels out and all that is left is the restoring force from the ground through the rim to the hub.
Now lets talk about the pre-tensioned hub.
You can guess the rest.. the tension cancels out and all that is left is the (resultant) compression on the lower spokes.
I've bracketed the (resultant) compression as I don't want it to cause you a problem.
Saying that one of the above examples would be able to support tension and not compression is not a valid answer. Both are true.

No spoke on a bicycle wheel is ever in compression at all. Ever.

So what I just said about R-sys wheels is wrong then, or for that matter any carbon spoked wheel?

Compression is the cause and contraction is the result

From your post above – do you actually understand what the words mean?
Erm, yes. one is a verb and the other a noun.

page three. here[/url]

Coud do with a belt drive, and a suntan, and some brakes, and some mudguards, and all of the things mentioned auf Deutsch above…. HTH!

Hmm bw any comments please?

I feel like I'm picking at this now but yes, just got home and it's still bothering me!… The analysis by Ian that I posted isn't complete and is only illustrative. He quotes this:
Loading is three upward point loads, 500N at very bottom of rim (centre of contact patch), 250N at each adjacent spoke/rim connection.
Doing a quick calculation with a Sapim leader spoke gives a middle section strength of 2872 N at a width of 1.8mm (the skinniest). So even considering that the spoke would (probably) only be loaded up to half it's strength (Park recomends around 550-1750 N in on it's tension meter calibration table) then it's reasonable to assume that in most normal situations it wouldn't be compressed beyond it's pre-tension. If it was then the nipple would separate from the rim, and the spoke would buckle once it contacted the rimtape. As rims really aren't that strong on their own when this would likely cause a flatspot.
Building a wheel loosely and with fewer spokes would only cause this event to happen at a lower force. Compression is not contraction. Compression is the cause and contraction is the result. This is even true in structures that have been pre-tensioned. It's just that the compression manifests itself as a reduction in tension.
And the whole difference in r-sys wheels is that they have spokes that have some strength in compression, not just in tension. That way they can stand up to compression with out such high pre-tension (as the article mentions) and mostly break as a result….

Apparently I'm rubbish coz I don't know which way up wheels go! 😉

I'm kind of in agreement with the posts above about Kiwis.. You can be driving as fast as you please down a twisty mountain road, and their big ugly Hilux is trying to do some mating thing with the back of your car…
Can't beat the place for handbrake fun on gravel roads though!

There we go..

Looking up here led me to here[/url].
If you can make it past the picture of his unicycle without laughing then there's a very good analysis. It's not semantics.. It's finite element analysis.

Here's his conclusions:

* There are 31 tensile spokes. On average they contribute 1.436 N (0.14 kg, just under a third of a pound) each to holding up the hub.
* There are 5 compressive spokes. On average they contribute 191.097N (19 kg, just over 42 lbs) each to holding up the hub.

And furthermore:

* The bottom spoke contributes 345.216 N of lift. The top spoke contributes only 12.487.
* The compressive spoke that contributes most (spoke 19: 345.216) contributes more than 15 times as much lift as the tensile spoke which contributes most (spoke 3: 21.955).
* The tensile spoke with the greatest impact on the lift figures is actually one pulling the hub down (spoke 15: -28.712).
* The least contributing compressive spoke (spoke 21: 60.955) contributes nearly three times as much as the most contributing tensile spoke (spoke 3: 21.955)

So basically, the bottom spokes have a far greater supporting role on the wheel than the top ones.

i just find it amazing that people will still argue until there blue in the face, when its quite clear to any rational thinking human being that they were wrong. but not going to admit it. strange

Not a problem, as I'm neither right nor wrong. You can roll my equivalence up to a tight cone and do with it what you will.

blimey… went our for a couple of hours and then this…
I promise you folks I'm not arguing something that is impossible, just an equivalent method… Did you know for instance that centrifugal force DOES exist if you talk about it from a rotating reference frame?

So if a spoke already has a tensile force exerted upon it, to physically COMPRESS the spoke you would need to exceed the tensile force already being applied in the opposite direction. Reduction of tension is not compression until this happens.

OK.. or to put it another way, to relieve the strain on the pre-stressed component you would have to put it under compression. That reduction in strain would relieve the strain and shorten it by the amount allowed by it's youngs modulus. This would happen until the stress became negative and the spoke bent.

now we're talking from the same page it's simple. And tracknico, you're wrong. If you're compressing a pre-tensioned component, then you're reducing the strain on it and therefore compressing it… It will be compressed until the compressive force is equal to the tensile force. After that it will bend. Most forces on a wheel aren't so harsh.

Clubber… Yes I understand what you mean. Overall the simplest way to describe the system is with the spokes being under compression. Any physics lecturer would be twatting you with a cricket bat if you didn't use the above…

Yes.. The resultant force is a compression.. ie. a reduction in tension. They are both the same mathematically. If you think about it in terms of your bike frame and the ground it gets simpler… the resultant force between your dropouts and the ground is compressive.

That's why tight wheels ate stronger – because the usually never lose tension when loaded. If they do ( become "in compression" ) then the spokes bend and the rim is likely to bend as it's unsupported.

yes too. I said that.

You cannot say that because there is a reduction in tension that the spoke is suddenly being compressed, it is not!

OK then.. So how come the lower spokes get shorter? I've said all along that the resultant force is compressive on the lower spokes. Under the equilibrium state they are in tension.

If a static system is in a pre-tensioned state then any compressive force acting upon it can be considered as a compressive force upon it's components. In the case of a wheel the compression would be relieved as a reduction of tension in the lower spokes and as an increase in compression around the rim and transferred to the hub as an increase in tension in the upper spokes. The other forces cancel out and leave just a compression in the lower spokes.

I give up. You're all welcome to think what you might, but it's entirely down to the spoke tension. We're all arguing over the fact of agreement that tension is equivalent to a reduction in compression. Fine. Please make a special effort to include atmospheric pressure when you check the gauge to inflate your tyres the next time.

And yes TJ.. They ARE in tension. The relief of tension is compression. Therefore the relief of tension has EVERYTHING to do with compressive strength.

If you look at it from an outside point of view, then who cares how tight the spokes are, it's all to do with how strong the wheels are in compression.

Already got that thanks, my point is that yours is just irrelevant to the discussion, seems most others are with me.

yep. me too. So lets go with the "my gang's bigger than your gang" logic and say you won. hubs hang from the upper spokes and tension has nothing to do with compressive strength.

In mathematical terms it is possible to describe the bottom spokes as being in compression. The have less tension than they had before, so if you count the starting (pre-tensioned) state as the zero state, you have put them "in compression". The reason they can support this compression is that the spoke has been pre-tensioned.

Thanks tj

well what do you want me to do? Teach you a physics a-level?

And Clubber.. yes spokes do cause deformation of hub flanges. I wasn't suggesting otherwise. Stress relieving while building will resolve this.

I can see this, I just can't see its relevance when discussing spoke tension in wheel builds.

well that's not my problem.

The spoke will bed in at the hub. If the wheel is built well then this won't be a problem.

That's what happens on loose wheels (or tight ones that have been loaded very heavily!) and what happens? The spokes bend and rotate in the spoke holes. They don't support load in compression.

rotation is not a problem. if they were built well then that wouldn't happen. If they were built with prolock or spoke freeze then also not a problem, unless they were not relieved. If they were not relieved enough when they were built then they might have this problem.

Cynic-al.. Can you imagine a spoke being compressed enough to equal its tension? It's the resultant overall force I'm talking about, not the force on individual spokes. Even so, when you even out the forces, wheels do stand on their lower spokes. All the other forces cancel out.

TJ… If you put tension on a spoke then it has compressive strength to resist that amount of tension. Above that point it will bend. I've got no prolems with that bit.

The net force on a bike wheel is compressive on the bottom spokes.

Ah, forget it. You are welcome to continue being wrong.

if wheels stand on the spokes below… how come the nipple doesnt thread into the rim? the spoke would just fall through into the tube?

It's because it's PRE-TENSIONED. If the spoke tension was too low then the greater force of the compression that the bike hit would be more than the tension in the spoke, so the compressive force would out-do the available strength. Then the rim would be the only bit opposing the compressive force, and if it was too great it would bend.

EDIT.. thanks TJ

Cables don't stretch either – it's all the cables & ferrules bedding in.

amen

it means you already have a mount for it on your frame. if your front mech clamps round the seat tube then no.

edit.. too slow!

jesus.. you lot are hilarious.

spokes have a LOT of strength in compression, provided they are pre-tensioned.

Olly, you have no idea how pre-tensioned engineering structures work.

The pre-tensioning is supported by the rim. any compressive forces on the rim act as a reduction on the tension… A reduction on a tensive force is a compressive force. And yes, 36 spoke hubs are stronger for exactly that reason.

and a flat spot has nothing to do with spoke tensions whatsoever.
unless your rims are made of cheese and the wheel was built by a chimp.

er… no.

A flat spot has everything to do with spoke tension. If you don't think so then you don't understand how wheels work. The supporting pressure of a spoke is equal to it's static tension. The wheel stands on its spokes; it doesn't hang on the ones above.

weirdly, after trying multiple rotors on my singlespeed, (lots of secondhanders lying around in the shop) I've found that Hayes rotors are the best. They're soft and wear out quickly, but have good bite.. I put an avid 160 on last week and nearly headbutted a tree, even after bedding in. People here whinge on about brake pads, but don't think about their rotors.

I can assure you that flat spots are not only caused when spokes are loose.

I wasn't saying that. You would need to hit a tight and even wheel a LOT harder to create a flat spot.. Hence why tyre pressures and pinch flats are an indication.

[edit].. Anyway, op has a crappily built wheel. PG spokes don't help; they should always be DB as they conform to loads better, and don't transfer so much force to the rim.

ooh.. sexy scrubbers!

I like the fact that you can only use organic pads with them.. Wouldn't last a winter on our shores!